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    <title>Document</title>
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<body>
    <script>
        // 箭头函数
        let play = function () {
            console.log('吃鸡');
        }
        play();

        let game = () => {
            console.log('王者');
        }
        game();

        // 1.如果形参只有一个，小括弧可以省略
        // let add=(num)=>{
        let add = num => {
            num++;
            console.log(num);
        }
        add(123);


        // 2.如果逻辑体只有一行代码，return 和{} 都可以省略
        let ball = score => score = score + 5;
        console.log(ball(10));

        // 3. this 上下文的this， 定义箭头函数位置的 this 
        const cook = function () {
            console.log(this);
            return () => {
                console.log(this);
            }
        }
        let temp = cook();
        temp();


        console.log('-----------------案例2-------------------');

        function Star(sex, age) {
            this.sex = sex;
            this.age = age;
            console.log(this);
            this.run = () => {
                console.log(this);
                console.log('吃饭');
            }
        }
        let lee = new Star('男', 22)
        lee.run();
    </script>
</body>

</html>